1. Field of the Invention
The present invention relates to a liquid crystal display and its driving method, and more particularly, to a liquid crystal display for eliminating MURA in a pixel matrix and driving method for the same.
2. Description of the Related Art
With a rapid development of monitor types, novel and colorful monitors with high resolution, e.g., liquid crystal displays (LCDs), are indispensable components used in various electronic products such as monitors for notebook computers, personal digital assistants (PDAs), digital cameras, and projectors. The demand for the novelty and colorful monitors has increased tremendously.
Referring to FIG. 1 showing a functional block diagram of a conventional liquid crystal display 10 using half source driver (HSD) technique, the liquid crystal display 10 includes a pixel matrix 12, a gate driver 14, and a source driver 16. The pixel matrix 12 includes a plurality of pixels, each pixel having three pixel units 20 indicating three primary colors, red, green, and blue. For example, the pixel matrix 12 with 1024 by 768 pixels contains a number of 1024×768×3 pixel units 20. The gate driver 14 periodically outputs a scanning signal to turn on each transistor 22 of the pixel units 20 row by row, meanwhile, each pixel units 20 is charged to a corresponding voltage based on a data signal from the source driver 16, to show various gray levels. After a row of pixel units is finished to be charged, the gate driver 14 stops outputting the scanning signal to this row, and then outputs the scanning signal to turn on the transistors 22 of the pixel units of the next row. Sequentially, until all pixel units 20 of the pixel matrix 12 finish charging, and the gate driver 14 outputs the scanning signal to the first row again and repeats the above-mentioned mechanism.
As to the conventional liquid crystal display, the gate driver 14 functions as a shift register. In other words, the gate driver 16 outputs a scanning signal to the pixel matrix 12 at a fixed interval. For instance, a pixel matrix 12 with 1024×768 pixels and its operating frequency with 60 Hz is provided, the display interval of each frame is about 16.67 ms (i.e., 1/60 second), such that an interval between two scanning signals applied on two row adjacent lines is about 21.7 μs (i.e., 16.67 ms/768). The pixel units 20 are charged and discharged by data voltage from the source driver 16 to show corresponding gray levels in the time period of 21.7 μs accordingly.
Referring to FIG. 1 and taking pixels T1-T8 as an example, during one frame time, pixels T1, T3, T6, T8 which directly couples to the source driver 16 are charged twice, whereas pixels T2, T4, T5, T7 which indirectly couples to the source driver 16 are charged once. Due to different and uniform charged times of the pixels T1-T8, MURA in the pixel matrix 12 is induced as shown in FIG. 2 which illustrates an exaggerated diagram. There are several straight lines in a single gray level frame, thereby weakening an image quality.